Rill erosion is a widespread form of soil erosion on loess slope surfaces. The rill formation, evolutionary mechanism, and the quantitative expression of rill erosion dynamic changes in a micro-topographic level are currently lacking, primarily owing to lack of finer-scale measurements. This work presented the rill erosion evolutionary process and their dynamic changes at different slope gradients, (12°, 18°) in a millimeter-scale analysis. We achieved it by constructing an artificial excavation in the field and performed a soil pan with dimensions of 8 m in length and 2 m in width, which were subjected to a constant rainfall intensity of 100 mm h⁻¹. The multiphase micro-geomorphologic changes during each rainfall phase were monitored using high-resolution terrestrial laser scanner (TLS). We noticed that the larger overland flow in the rill corresponded to more pronounced fluctuations in the cross-section lines of the rill bed. Also, with more the number of rills, the more easily the overland flow was dispersed, which required a larger slope gradient to resume the erosion and fill processes. Erosion rate and fill rate were highly correlated in general, and they increased abruptly at 70–90°. Due to the presence of swelling minerals, the loess surface expanded rapidly after encountering water in the early stage of rainfall. Therefore, the amount and rate of erosion on the slopes were underestimated. Understanding the detailed evolution process of rill erosion from a micro-perspective can provide a valuable reference for the development law of the initial stage of slope erosion in the loess region where erosion is extremely serious.

沟蚀是黄土坡面土壤侵蚀的一种普遍形式。当前缺乏在微地形水平上的小溪形成，演化机制和小溪侵蚀动态变化的定量表达，这主要是由于缺乏更精细的测量结果。这项工作在毫米尺度分析中介绍了钻蚀侵蚀的演化过程及其在不同坡度（12°，18°）下的动态变化。我们通过在野外进行人工开挖来实现这一目标，并进行了长8 m，宽2 m的土壤盘，这些盘承受了100 mm h ^-1的恒定降雨强度。使用高分辨率地面激光扫描仪（TLS）监测每个降雨阶段的多相微地貌变化。我们注意到，小溪中较大的陆上水流对应于小床横截面线的明显波动。而且，随着小溪数量的增加，陆上水流越容易分散，这就需要更大的坡度梯度才能恢复侵蚀和填土过程。侵蚀率和填充率通常高度相关，并且在70–90°时突然增加。由于存在溶胀的矿物，在降雨初期，黄土表面在遇水后迅速膨胀。因此，低估了斜坡的侵蚀量和速率。